This is a proposal for the NHLBI R21 Innovative Research Grant Program, which encourages the analysis of existing data sets to explore new hypotheses. Endotracheal intubation (ETI) is the insertion of a plastic tube into the trachea (throat) to assist the breathing of a patient with a critical illness such as cardiopulmonary arrest, heart failure, respiratory failure or major trauma. While ETI is performed by physicians in the hospital, resuscitation usually begins in the out-of- hospital setting under the care of paramedics. In many fields of clinical practice, medical errors are known to be associated with both practitioner procedural volume as well as patient outcome. Many studies have found that paramedics commit errors when performing ETI. Furthermore in a preliminary study, we found that paramedics perform ETI infrequently in clinical practice and at frequencies far below that needed to maintain procedural proficiency, safety and effectiveness. Few direct links between the procedure, success and errors, and patients outcomes (including hospital course or resource utilization) exist. We posit that ETI performed by paramedics with low procedural experience may adversely affect patient outcome and hospital course of care. The goal of this study is to determine if paramedic (ETI) procedural experience is associated with patient outcomes and in-hospital course of care. In the proposed study we will probabilistically link three publicly- available statewide administrative databases encompassing paramedic patient encounters, admitted inpatients and deaths. We will apply multivariable regression to the linked data set to evaluate the connection between paramedic ETI procedural experience (annual volume of ETI), outcomes (mortality and in-hospital adverse events) and in-hospital resource utilization. We propose a new collaboration between research teams at the Universities of Pittsburgh and Utah, which have expertise in the areas of out-of-hospital care, health services research, the analysis of large-scale data sets and probabilistic linkage. These findings may demonstrate that paramedic ETI experience directly impacts patient outcome, and may promote major changes in the design and delivery of this life-saving out- of-hospital intervention. These findings would also confirm this linkage method as a new, powerful tool to evaluate the earliest portion of acute medical care - that begun in the out-of-hospital setting.